Antioxidative pyranonigrins in rice mold starters and their suppressive effect on the expression of blood adhesion molecules

Antioxidants having a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity in rice mold starters, which are used for the preparation of various Japanese fermented foods, and their effectiveness against the expression of blood adhesion molecules were examined. An antioxidant was isolated from the rice mold starters used for shochu and identified as pyranonigrin-S (PG-S) by H-1-NMR, C-13-NMR, and FAB-MS analyses. It was a derivative of pyranonigrin-A (PG-A), which has been isolated as an antioxidant from the rice mold starters. Pyranonigrins PG-A and PG-S were found to exist in spores on rice mold starters which had been prepared by Aspergillus awamori, A. kawachii, and A. saitoi. PG-S exhibited a higher level of DPPH radical scavenging activity than PG-A. PG-A was found to have a significant suppressive effect on the expression of vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs) induced by tumor necrosis factor-a (TNF-alpha) (P < 0.05).